Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds one genuinely useful behavioral fact – 'metadata only' – signaling it returns taxonomy metadata rather than products, but says nothing about how store context is resolved or whether results are cached.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single compact sentence that front-loads the resource and follows with scope qualifiers. No padding, though it is arguably too terse given the undocumented parameters.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return values need not be explained. However, for a tool requiring store-specific identifiers with zero schema documentation, the description should at least hint at how shop_id/store_slug/postal_code are sourced; that gap leaves it only minimally complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

All three required parameters (shop_id, store_slug, postal_code) have 0% schema description coverage, and the description adds no parameter meaning whatsoever – it never mentions any of them. With low coverage the description is expected to compensate, and it does not, so the agent gets no help on what these IDs are or where to obtain them.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Names a specific resource (Instacart store department/category taxonomy) and adds scope detail ('two levels deep, metadata only') plus concrete examples (Produce, Dairy & Eggs, Bakery). An agent can distinguish it from instacart_search or instacart_stores, though the description never explicitly contrasts itself with those siblings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

No when-to-use guidance is given. The description never says when to reach for the department taxonomy versus instacart_search, instacart_stores, or instacart_trending, nor does it state prerequisites. The agent must infer usage entirely.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.